Driving mechanism for centrifugal separators



DRIVING MECHANISM FOR CENTRIFUGAL SEPARATORS Filed Feb. 5, 1946 '4Sheets-Sheet l J- E. THOLL.

DRIVING MECHANISM FOR CENTRIFUGAL SEPARATORS Filed Feb. 5, 1.946

4 Sheet s 2 w HQSH DRIVING MECHANISM FOR CENTRIFUGAL SEPARATORS FiledFeb. 5, 1946 4 Sheets-Sheet 4 Patented May 8, 1951 UNITED STATES TENTOFFICE DRIVING MECHANISM FOR CENTRIFUGAL SEPARATORS Application February5, 1946, Serial No. 645,519

Claims.

In my earlier Patent No. 2,112,430, granted March 29, 1938, I havedescribed and claimed a two-speed drive for centrifugal separators ofthe type much used in sugar refiners and for other purposes where it ishighly desirable to drive the basket at a high speed during thecentrifuging operation, and then to operate it at a very slow anduniform speed during unloading or discharging. This mechanism has provedexceptionally satisfactory and has enjoyed a Wide acceptance in thetrade.

The present invention aims further to improve and to perfect themechanism disclosed in said patent with a view to reducing the rate ofWear created in the parts of said mechanism; reducing the care andattention required by it; and generally increasing its serviceability.

The nature of the invention will be readily understood from thefollowing description when read in connection with the accompanyingdrawings, and the novel features will be particularly pointed out in theappended claims.

In the drawings,

Fig. 1 is a side elevation of a mechanism con structed in accordancewith this invention;

Fig. 2 is a plan view of the mechanism shown in Fig. 1, with some partsshown in horizontal section;

Fig; 3 is a sectional view on the line 3-3, Fig. 2;

Fig. 4 is a partial horizontal section taken substantially on the line44 of Fig. 3;

Fig. 5 is a half-sectional view showin a modified embodiment of theinvention; and

Fig. 6 is a vertical, sectional view showing on a larger scale portionsof the clutch illustrated in Fig. 3.

Referring first to Figs. 1 to 4, inclusive, the construction there shownillustrates the invention as applied to a suspended type of centrifugal,the basket being indicated in Fig. 1 at 2, supported, on a verticalshaft 3, which may either be a continuation of the shaft 4 of the maindriving motor 5, or may be an integral part of that shaft.

In any event, the basket shaft and the motor shaft are connectedtogether to revolve in unison so that they function as a single shaft.

For the purpose of driving the basket at a slow speed, during thedischarging operation, a much smaller supplemental motor 6, Figs. 1 and2, is provided and it isv connected with the shaft 4 through a gearreduction mechanism comprising a worm 1, Figs. 2 and 3, fast on theshaft 6 of the supplemental motor and meshing with; a worm wheel 8. Thisdrive takes place through an overrunning clutch comprising an outersleeve 10, Figs. 3 and 4, and an inner sleeve II. The former is boltedto the upper end of a cup-shaped coupling [2 which is secured to theupper end of the motor shaft i, while the latter is keyed to a stubshaft l3 integral with the central hub member 8 of the worm gear 8. Thusthe outer and inner clutch sleeves l0 and I l are connected positivelywith their respective motors 5 and 6 to be driven thereby.

Interposed between these two clutch sleeves are severalpower-transmittin cams l5 shaped approximately as shown in Fig. 4. Eachcam is an elongated flat-sided bar and its inner edge is provided with arib a resting loosely in a groove formed in the periphery of the sleeveI i, while its outer edge is of cam formation, the distance between therib a and the two corners b and c of the cam shown in the center of saidfigure differing quite substantially. Also, the outer edge surface ofthe cam 15 between the corners b and c has a rounded eccentric form.From the opposite ends of each of these cam members two pins e projectand bear normally against the inner surfaces of two flanged collars ddwhich are carried by the inner sleeve II, as best shown in Fig. 6. Theyprevent any substantial radial movement of the cams outwardly. Also,light springs, one of which is shown at IS in Fig. 4, act on therespective pins 6 to give the cams a slight initial bias backwardly withreference to their direction of rotation. A washer !9, Fig. 6, issecured by a screw l9 to the lower end of the shaft l3 where it supportsthe lower end of the inner sleeve H and cooperates with another part ofthe stub shaft engaging the upper end of said sleeve to hold it in theproper axial position in the mechanism.

Assuming that the small motor 6 is driving the inner sleeve il in thedirection indicated by the arrow in Fig. 4, and that the outer sleeve Itis stationary, or is revolving in th same direction at a slower speedthan the inner sleeve, then each a cam IE will be tipped in a clockwisedirection, thus bringing the radially higher part of each cam intocontact with the inner surface of the sleeve Hi and causing all the camsin the series to jam between the two sleeves and thus to pick up theouter sleeve in rotation with the inner one. At this time, therefore,the motor 5 will drive the basket shaft 3 through the sleeves Ill and Hand the cams l5. The speed of rotation will be slow because of the gearreduction mechanism through which the drive is effected.

I If, now, the control switch of the main motor should be closed and thelatter motor started into rotation, thus revolving the outer sleeve illat a higher speed than the inner sleeve, then the contact of the innersurface of the outer sleeve with the cams [5 will tip them in acounterclockwise direction and thus interrupt the connections throughwhich the small motor has been driving the outer sleeve. If, also, thepower is shut off the supplemental motor, all of the clutch parts,except the outer sleeve ID, will stop and remain stationary. Later, whenthe power is cut off the main motor 5 and is turned on to thesupplemental motor ii, the cams i5 will again operate automatically toshift the drive for the shaft 4 back again to the inner sleeve ii. Inother words, the action of these cams in the clutch is to shift thedrive automatically to the sleeve revolving at the higher speed.

When the cams !5 are stationary they do not bear against the innersurface of the outer sleeve with sufficient pressure to create anysubstantial degree of wear, and such wear is further reduced by thelubrication of said inner surface and of the cams themselves. Becausethe cams are non-rotating, they cannot be revolved around their ownaxes, as would be the case if they were rolls.

This arrangement, therefore, contributes materially to the reliabilityand length of life of the driving mechanism, reducing maintenance, bothin cost of parts and in the labor involved.

The motor 5 is equipped with bearings supporting its shaft i forrotation around a fixed axis, and the clutch sleeves l0 and l l arespaced apart by upper and lower ball bearings ll and i8, respectively,which support the outer sleeve for rotation around the same axis. Inaddition, the hub member 8 of the worm gear 8 is provided with anupwardly extending stub shaft section 8" which also is supported by aset of ball bearings mounted in the casing or housing 2| that enclosesthe entire clutch mechanism and the driving elements above referred to.In the particular arrangement shown this casing 2i and the end sectionof the casing for the motor 6, are cast as an integral piece, thusproviding a firm, rigid support for the running parts.

A further feature of this invention resides in a novel lubricatingsystem so organized as to feed oil automatically to all of the frictionsurfaces of this mechanism. Referring again to Fig. 3, it will beobserved that an oil well 22 is provided in the lower part of the casing2|, and a port leads from the bottom of this well directly into a pump23, Figs. 1 and 3, which is secured to the side of the casing. Mountedin this pump assembly is a plunger 24 extending radially inward with itsinner end bearing against the outer eccentric surface 1 of the upperpart of the coupling member [2. This member is always in rotation whenthe mechanism is in operation, and it is so designed as to cooperatewith a concealed spring acting on the plunger to impart a shortreciprocating stroke to it. Cooperating with this plunger are upper andlower valves (not shown) as are common in a plunger pump construction toforce oil taken from the well 22 up through the pump and the dischargeducts 25 and 26 formed in the casing 2| and in the casing cap 2 I" intothe transparent sight glass 2'! at the top of the cap. The oil sodelivered overflows into the top of a nipple g in said cap and runs downthrough the bore of said nipple into an oil distributing chamber orreservoir 28, the bottom of which is clos by the thimble 28'.

From this receptacle oil flows through a central discharge aperture inthe thimble 28 into a bore h in the hub 8 and then downwardly throughsaid bore and through a connecting radial duct into and through theupper ball bearing ll. It continues downwardly along the inner surfaceof the clutch sleeve it, through the lower ball bearing 18, and isdischarged by centrifugal action through ports 7c into the oil well 22.Preferably the bottom of this oil well is inclined toward the left, Fig.3, so as to drain the oil toward the inlet to the pump 23.

Some of the oil delivered to the chamber 28 flows through an aperture ininto the upper ball bearing 29 and is then caught in a cup 11. fromwhich a spout 38 conducts it to the worm i. The housing for this worm isshaped to provide a trough 3! which retains some oil continuously incontact with the lower surface of the worm, the

1 surplus overflowing the inner edge of the trough into the oil well 22.

The caps 2| and T, Fig. 2, are removable to permit access to, andinspection of, the enclosed parts, and a plug 32, Fig. 3, is provided inthe cap 2 l for this purpose.

With this arrangement exceptionally good lubrication of all of thefriction surfaces is maintained without attention on the part of theworkmen, except to see that an ample oil supply is maintained in thewell. Preferably an oil seal 33, 3, is provided in the shank of thecoupling l2 to close the joint between this member and the motor shaft4.

In the construction above described. the main motor 5 has been mountedbelow the clutch mechanism. In some cases, however, it is preferable toarrange these parts in a reverse relationship. Such a construction isshown in Fig. 5 in which the parts corresponding to those abovedescribed are designated by the same, but primed, numerals. The motor 5is mounted above the clutch and its shaft 4 extends downwardly throughthe clutch mechanism and through the brake drum 3%, fast on it, into thesuspension head 35 at or below which it is coupled to the basket shaft3'. Upper and lower ball bearings 36 and 3?, respectively, support thisshaft and are themselves supported in the machine frame 38 which, inthis embodiment of the invention, forms the casing for the driving andclutch mechanisms. In the clutch the sleeve H is loose on the shaft ibut is secured to the hub of the worm gear 8 so that it rotatestherewith.

Thus it approximately takes the place of the stub shaft [3 and thesleeve H of the construction above described. Consequently, theoperation of this mechanism is exactly like that disclosed in connectionwith Figs. 1 to 4, inclusive, the same clutch mechanism being includedin this modification.

A similar lubricating system also is provided comprising the pump 23discharging through an outside pipe connection ii] into the sight glass21. From this glass the oil flows through a lateral pipe ll into ashallow annular receptacle or chamber 42 from which an oil duct 43 leadslubricant into the uppermost ball bearing 36. From there it flows bygravity through ducts o in the hub of the worm gear down into andthrough the two ball bearings of the clutch, lubricates the innersurface of the sleeve i0, and is discharged through outlets it into theoil well 22'. Another tube i leads oil from the chamber 42 to thesurface of the worm 2" with which a trough 3! also i associated, as inthe construction above described. Any oil overflowing the walls of theannular chamber 42 isconducted back into. the oil well through the duct55. A similar provision is made for taking care of overflow from the oilchamber 28, shown in Fig 3, where the duct 29 carries off the surplusand leads it back into such a position that it ultimately flows into theoil well.

Because the plungers for both the pumps 23 and 23 should havelubrication, I prefer to drill a small hole axially through each plungerfor its entire length so that upon each inward stroke a little oil willbe forced backward through the plunger and discharged against theeccentric surfaces and which operate it.

The foregoing features materially improve the construction shown in myearlier patent, by reducing the rate of Wear inthe driving mechanism,both because of the changes in organization of this mechanism and alsobecause of the provision made for automatically lubricating all of thefriction surfaces. This, in turn, results in reducing the care andattention required by the workman, eliminating much of the necessity forrepair parts, and correspondingly reducing maintenance costs,

While I have herein shown and described preferred embodiments ofmyin-v-ention, it will be evident that the invention may be embodied inother forms without departing from th spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. The combination with a centrifugal separator including a basket shaftand a, basket fixed thereon, of a main electric motor directly connectedwith the basket shaft to revolve the basket at normal speeds, a lowspeed driving shaft supported adjacent to one end of the basket shaft, aclutch comprising inner and outer sleeves concentric with each other andwith said basket shaft and low speed driving shaft said inner sleevebeing secured to the low speed driving shaft, a series of pivotallysupported elongated cams parallel with said low speed driving shaft andinterposed between said sleeves, means securing said outer sleeve tosaid shaft for rotation therewith, a normally idle supplemental motor ofsmaller horse power than said main motor, a reduction gearing throughwhich said supplemental motor is connected in driving relationship withthe low speed shaft, said supplemental motor in operation being adaptedto drive the basket shaft through the said clutch when the main electricmotor is not running, said reduction gearing connections holding saidsleeve substantially stationary when said supplemental motor is notrunning, means supporting said cams on said inner sleeve for rotationsubstantially in unison therewith but against rotation when the innersleeve is stationary, said cams being shaped to jam against, and make adriving engagement with, the outer sleeve when the inner sleeve revolvesfaster than said outer sleeve and to release the latter sleeveautomatically when it revolves faster than the inner sleeve, wherebysaid inner sleeve and said cams remain substantially stationary whensaid shaft is driven through said outer sleeve by said main motor.

2. A combination according to preceding claim 1, including a casing inwhich said clutch, said reduction-gearing and a part, at least, of saidshaft are enclosed, said casing including an oil well, a pump driven bya part connected with said outer sleeve and revolving with it, an oilreceptacle located above said reduction gearing and said clutch,connections for conducting'oil from said pump into said receptacle, andmeans for conducting oil from said receptacle by gravity to the variousfriction surfaces of said reduction gearing and said clutch.

3. The combination with a centrifugal separator including a basket shaftand a basket fixed thereon, of a main electric motor directly connectedwith the basket shaft to revolve the basket at normal speeds, a lowspeed driving shaft, means for supporting the low speed shaft in fixedaxial alignment with the said basket shaft, a normally idle supplementalmotor of smaller horse power than said main motor, a clutch foroperatively connecting the basket shaft and main electric motor with thelow speed driving shaft, said clutch comprising inner and outer sleevesconcentric with each other and with said basket shaft and low speeddriving shaft, a series of pivotally supported cams interposed betweenthe said sleeves, means securing said outer sleeve to the basket shaft,a reduction gearing through which said supplemental motor is connectedwith the inner sleeve, said reduction gearing consisting of a worm andworm wheel fixed to the low speed driving shaft, said connectionsholding said inner sleeve substantially stationary when saidsupplemental motor is not running, means supporting said cams on saidinner sleeve for rota tion substantially in unison therewith but againstrotation when the inner sleeve is stationary, said cams being shaped tojam against and make a driving engagement with the outer sleeve and todrive the basket shaft when the inner sleeve revolves faster than thesaid outer sleeve, and said low speed driving shaft and speed reductiongearing cooperating with the clutch to hold the inner sleeve and camsagainst rotative movement when the outer sleeve is driven by the maindriving motor and thereby operating to reduce wear at the inner engagingsurface of the clutch.

4. The combination with a centrifugal separator including a basket, of amain electric motor directly connected with the basket shaft to revolvethe basket at normal speeds, a clutch mounted on said shaft andcomprising inner and outer sleeves concentric with each other and withsaid shaft, a series of elongated cams parallel with said shaft andinterposed between said sleeves, means securing said outer sleeve tosaid shaft for rotation therewith, a normally idle supplemental motor ofsmaller horse power than said main motor, a worm gear mounted on saidshaft to rotate around it, a worm driven by said supplemental motor andmeshing with said worm gear to drive it in the normal direction ofrotation of said shaft, means connecting said inner clutch sleeve withsaid worm gear to cause it to revolve in unison with said gear, meanssupporting said cams on said inner sleeve for rotation therewith butagainst rotation relatively thereto when the inner sleeve is stationary,said cams being shaped to jam against the inner surface of the outersleeve and to make driving engagement therewith when the inner sleeverevolves faster than the outer sleeve and to free the outer sleeveautomatically when the latter revolves faster than the inner sleeve,whereby said inner sleeve and said cams remain substantially stationarywhen said shaft is driven through said outer sleeve by said main motor,including a casing in which said clutch and said worm and worm gear areenclosed, together with a p0r- 'tion of said shaft, an oil well in saidcasing, a

pump connected with said oil well to draw oil therefrom, means revolvingwith said outer clutch sleeve for driving said pump, oil distributingmeans located in the upper part of said casing, connections from thedischarge side of said pump for conducting oil therefrom to saiddistributing means, said oil distributing means including parts fordelivering oil to the various friction surfaces of said clutch and saidworm and worm gear.

5. The combination with a centrifugal separator including a basket, of amain electric motor directly connected with the basket shaft to revolvethe basket at normal speeds, a clutch mounted on said shaft andcomprising inner and outer sleeves concentric with each other and withsaid shaft, a series of elongated cams parallel with said shaft andinterposed between said sleeves, means securing said outer sleeve tosaid shaft for rotation therewith, a normally idle supplemental motor ofsmaller horse power than said main motor, a worm gear mounted on saidshaft to rotate around it, a worm driven by said supplemental motor andmeshing with said Worm gear to drive it in the normal direction ofrotation of said shaft, means connecting said inner clutch sleeve withsaid worm gear to cause it to revolve in unison with said gear, meanssupporting said cams on said inner sleeve for rotation therewith butagainst rotation relatively thereto When the inner sleeve is stationary,said cams bein shaped to jam against the inner surface of the outersleeve and to make driving engagement therewith when the inner sleeverevolves faster than the outer sleeve and to free the outer sleeveautomatically when the latter revolves faster than the inner sleeve,whereby said inner sleeve and said cams remain substantially stationarywhen said shaft is driven through said outer sleeve by said main motor,including ball bearing located between said clutch sleeves andmaintaining them in fixed spaced relationship to each other, andadditional ball bearings supporting said shaft above said clutch, acasing in which said clutch, said worm and said worm gear and a portionof said shaft are enclosed, an oil well in said casing, a pump connectedwith said oil well to draw oil therefrom, an eccentric revolving withsaid outer sleeve for driving said pump, an oil receptacle in saidcasing above said worm and said ball bearings, and means for conductingoil from said receptacle by gravity to said worm, said ball bearings andthe friction urfaces of said clutch.

JOHN E. THOLL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,235,633 Anderson et a1 Aug. 7,1917 1,545,065 Randolph et a1 Jul 7, 1925' 1,952,461 Roos Mar. 27, 19342,112,430 Tholl Mar. 29, 1938

